1. Technical Field
The present invention relates to a high-voltage system control device for a vehicle that controls a high-voltage system provided to a vehicle with an electric motor.
2. Related Art
There are two types of vehicles having an electric motor as a power source: in a narrow-definition, electric vehicle (EV) including only an electric motor as a power source; and in a broad definition, a hybrid vehicle (HEV) including an electric motor and an internal-combustion engine as power sources. In these vehicles, the electric motor is connected to a battery such as a rechargeable battery via an inverter and the section from the battery to the electric motor constitutes a high-voltage system. When the vehicle is crashed into a preceding vehicle or an obstacle, an air-bag is activated to protect a passenger. Further, since the crash may damage the battery in a high-voltage state leading to electrical shock due to a leakage of, the high-voltage system is automatically cut off upon the detection of a crash, in other words, an automatic disconnection is performed.
Japanese Unexamined Patent Application Publication (JP-A) No. 2005-20952 discloses a hybrid vehicle which turns off a main relay of a system when a crash prediction signal is received. JP-A No. 2006-20450 discloses a control device of a hybrid vehicle which turns off a strong electric relay when the vehicle is crashed or a crash is predicted.
JP-A No. 2006-143141 discloses a high-voltage cut-off system of a hybrid vehicle which is disconnects an electric connection between a high-voltage battery and an inverter when a crash is predicted. JP-A No. 2007-129827 discloses a brake assist system which performs regenerative braking by a motor when entering a range requiring a pre-crash brake after a crash is predicted. In this brake assist system, when a possibility of a crash is determined, a drive force distribution ratio to a motor is set higher than a drive force distribution ratio to an engine. When the vehicle is determined to enter a range requiring the brake activation, regenerative braking force is generated by the motor.
When a vehicle is provided with an inter-vehicle distance detection unit, an inter-vehicle distance between the vehicle and a preceding vehicle or an obstacle can be detected. In a vehicle with an automatic brake, which automatically activates a brake, in addition to the inter-vehicle distance detection unit, a pre-crash control which automatically activates the brake can be performed by predicting a crash according to the inter-vehicle distance. By performing the pre-crash control, even when there is a preceding vehicle or an obstacle in front of the vehicle, a crash can be avoided by automatically activating the brake and damage of a crash can be reduced.
However, as described above, danger of a high-voltage system may not be sufficiently avoided when the high-voltage system is cut off after a crash is detected.